This invention relates to controlled deflection rolls such as used in the papermaking industry. However, controlled deflection rolls can be used in any application wherein the deflection, or crown--as reverse deflection is sometimes called, of the roll face is desired to be controlled with respect to a nip with a mating roll to provide either a straight line of nip contact or a matching contour of the nip line of contact between the rolls.
More particularly, this invention relates to so-called self-loading controlled deflection press rolls. In this type of controlled deflection roll, the roll shell is pivotally-movable, in a translational sense, relative to the supporting fixed roll shaft from an initial position spaced from the mating roll to a second position with the mating roll shells in contact. It accomplishes this without moving its shaft and without external lever arms, hence the term "self-loading".
This self-loading operation is known in the art, such as, for example, in U.S. Pat. Nos. 3,885,283, 4,213,232, 4,249,290 and 4,520,723. However, prior self-loading controlled deflection rolls either utilized a yoke having parallel sliding surfaces operating in conjunction with corresponding surfaces on either end of the roll shaft, or utilized one or more shoes supporting the roll longitudinally along the length of the roll to position the roll shell radially into contact with the mating roll, control the deflection of the roll shell and provide the nipping force, or both. Providing all of these functions by the same shell-supporting pressure shoes causes increased wear on these pressure shoes to the detriment of the roll's operational service time.
In addition, the sliding action of the yoke against the mating surfaces on the roll support shaft requires increased energy to load and unload the roll, especially if the bearings bind. These sliding surfaces also require close tolerances to operate accurately and prevent vibration. Therefore, they are expensive to manufacture. If the tolerances are too loose, the movement of the roll shell, and nipping engagement with another roll, will not be accurate.